T2 Sensor for Thelin pellet stoves. Part # 00-0005-0028. The T-2 Sensor or Proof of Fire is what ultimately gets the unit into what we call the “Run Mode” after initial Start-Up where High, Medium & Low can be adjusted. It also controls shut-down of the unit after unit has been pushed to off, the T-2 will cool down typically 30 minutes & shut unit down.